The present invention relates to methods for modification of proteins and, more specifically, to methods for the chemical derivatization of proteins.
The most common method of preparation of proteins involves preparation of recombinant DNA plasmid encoding the desired amino acid sequence, introduction of the recombinant DNA into prokaryotic or eukaryotic cells, and expression of the encoded protein in the cells. To simplify subsequent purification of these proteins recombinant DNA sequences commonly incorporate a nucleotide sequence encoding an oligohistidine tag at the beginning or at the end of the polypeptide chain. During purification of recombinant proteins the oligohistidine sequence is bound on chromatography columns functionalized by aminocarboxylate groups binding divalent metal cations resulting in its separation from other proteins that does not contain oligohistidine sequences.
Chemical derivatization of native and recombinant proteins is used for modification of their physical, chemical, and biological properties, and for their immobilization on interfaces. Existing methods of chemical derivatization of proteins involve formation of covalent bonds with amino acid residues of the polypeptide chain of proteins using reactions of alkylation, acylation, formation of thioureas, formation of mixed disulfides, as well as other reactions. These reactions are frequently not selective and provide complex mixtures of products.